Reset dropdown box value based on another dropdown box in Edit Mode on SharePoint

I have created SharePoint form in Power Apps. The form includes a dropdown box based off a SharePoint choice column (we will call this dropdown box “Access Type”). The Access Type dropdown box has two choices, “Global BU” and “Entity Local”. Depending on the selected choice, a child dropdown box will become visible. So for example, if I select choice “Global BU” from the “Access Type” dropdown box, dropdown box A will appear. If I select choice “Entity Local” from the “Access Type” dropdown box, dropdown box B will appear.

Issue:

If I select “Global BU” from the Access type dropdown box, and then select a value from dropdown box A, and then change my mind and select choice “Entity Local” from the Access Type dropdown box, any value already selected in dropdown box A will reset via the following formula (added to the Reset property in drop down box A):

Not(Find(ACCESSTYPE.Selected.Value,"Global BU")>0)

This works fine in New Form Mode but does not work in Edit Mode on SharePoint. Data previously entered in dropdown box A still gets saved to SharePoint.